A blog about some of the Antarctica Weddell seal population study field research work and outreach efforts during the Weddell seal pupping season in the Erebus Bay region of Antarctica's Ross Sea. Weddell seal images and recordings obtained under NMFS Permit Nos. 1032-1917, 17236, and 21158. More information at http://WeddellSealScience.com

06 November 2013

A Very Old Weddell Seal Mom Returns, Gives Birth To Her 21st Pup!

She's back! And she's making Weddell seal population project history.

The B-009 field team was working in the Hutton Cliffs area of Erebus Bay when they located a remarkable mom and her new pup. According to project lead scientist Jay Rotella, this extraordinary Weddell mom, known in the project database as SPENO 5970, is now 30 years old and has given birth to her 21st pup. This makes her among the oldest Weddell seals recorded in the 45 year history of the project, (the oldest on record being 33). At 21 pups to date, she is the project record holder for producing the most pups over a lifetime. We first wrote about this Weddell super-mom last season, when she was located by field team members in 2012 at Hutton Cliffs.

Project lead scientist Bob Garrott working with the field team in Antarctica took this photo yesterday of field team leader Thierry Chambert affixing a tag to the new pup's rear flipper as mother SPENO 5970 looks on.

As with all of SPENO 5970's previous 20 pups, her new pup was born at Hutton Cliffs pupping colony in the Erebus Bay study area. Weddell seals are philopatric, meaning they show a strong fidelity to the area where they were born, and usually return to the same area to have their own pups.

SPENO 5970 was born in 1983 at a pupping colony in the Erebus Bay study area referred to as Glacier Tongue North Base. This pupping colony is relatively close to the Hutton Cliffs pupping colony, where all of SPENO 5970's 21 pups have been born over her reproductive life to date.

After SPENO 5970 was born at North Base in 1983, she disappeared from the Weddell population for two years before first returning to the study area as a two year old youngster in 1985. She returned again in 1988 and 1989 as a pre-breeder, meaning she had not yet had a pup. Then in 1990 she returned and gave birth to her first pup at Hutton Cliffs.

Project lead scientist Jay Rotella notes that what is so remarkable about this Weddell mom is that she has had pups at ages 8, 9, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 29, and 30. Weddell seal moms live an average of 15 years, and usually have around 2 pups every 3 years, so this long life and frequency of pupping is quite unusual. "She had pups in every year from 1990 to present except for 1993, 2010, and 2011," says Rotella.

SPENO 5970 with her 21st pup in a photo by field team member Terrill Paterson.

Because of the longterm dataset of the Weddell seal population project, the researchers are able to keep track of the animals in the study area and access data on over four decades of seals and several generations. Working with the extensive database, Jay Rotella was able to determine that of SPENO 5970's first 20 pups, 10 were females and 10 were males. "Of those offspring, 2 sons and 2 daughters have been seen again, which is right in line with what we'd expect based on other analyses [indicating] that roughly 20% of the seals make it to adulthood."

Of SPENO 5970's surviving offspring, two daughters have returned to the pupping colonies to give birth themselves. One of those daughters is 22 years old and has produced 13 pups so far. One of that daughter's pups--a granddaughter of SPENO 5970--has gone on to have 5 pups herself.

SPENO 5970's daughter 8731AA with her new pup (SPENO 5970's granddaughter) in a photo by field team member Terrill Paterson.

"Through her own pups and those of her daughters and grandaughters, she is responsible for 40 pups so far," notes Rotella. And this does not even take into account how many offspring she may be responsible for through her sons!

SPENO 5970's daughter, 8731AA, in a photo by field team member Terrill Paterson.